Method for the thermographic inspection of nonmetallic materials, particularly coated nonmetallic materials, as well as method for the production thereof and an object produced according to the method

Abstract

A method for the thermographic inspection of nonmetallic materials, particularly coated nonmetallic materials, is provided. The method includes heating at least one part of the surface of the nonmetallic material, preferably a part of the surface furnished with a nonmetallic coating, by a short energy pulse, preferably a light pulse, or by periodic input of heat, and recording the temporal and spatial temperature profile at least at a plurality of successive time points.

Description

CROSS REFERENCE TO RELATED APPLICATIONSThis application is a U.S. National Stage Entry under 35 U.S.C. §371 of International Application No. PCT / EP2009 / 002284, filed on Mar. 28, 2009, which claims benefit under 35 U.S.C. §119 of German Patent Application No. 10 2008 016 272.8, filed Mar. 28, 2008, the entire contents of both of which are incorporated herein by reference.BACKGROUND OF THE INVENTION1. Field of the InventionThe invention relates to a method for the thermographic inspection of nonmetallic materials, particularly coated nonmetallic materials.2. Description of Related ArtMethods for thermographic inspection have been used to date, for example, for the inspection of metallic materials for flaws of the material itself or of coatings applied to the material.WO 2006 / 037359 A1 discloses a thermographic method in which the temporal profile of the surface temperature is analyzed, with this analysis being undertaken as a function of time logarithms and temperature logarithms. Inv...

AI Technical Summary

Problems solved by technology

However, a problem has hitherto existed in inspecting or even measuring the thickness or completeness of a coating application of thin nonmetallic layers on nonmetallic materials, such as, for example, protective layers on ceramic materials.

This problem is generally found to be all the more difficult as these layers become more similar.

In particular, ceramic layers or layers containing particles, including sintered particles, can barely be distinguished optically or are not at all distinguishable from the coated ceramic substrate, for example.

The optical inspection had to be conducted during the spraying, because, after thermal fixation, this layer can nearly no longer be perceived using visual means.

Further known was the investigation of these layers after spraying by means of a spot-check-like scratch test, which resulted, however, in the destruction of the layer at least at the respective site of the test.

Not only immensely high costs for loss of a crucible and its material but also the danger due to liquid silicon leaking out at very high temperature make clear the need for these improved methods.

An inspection and metrological problem thus existed for this very material-layer system combination in that the thin coating application could hardly be distinguished optically from the underlying ceramic support material.

Consequently, there initially also existed the presumption that thermal measurements, particularly in the infrared spectral region, would not provide any significant results, and the inventors were all the more surprised when they obtained the results described below.

Without this step, serious variations were found in the results, which would have led to dramatic erroneous evaluations of the layer thicknesses as well as of the intactness of the layer system.

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